Based on sophisticated clinical descriptions and characteristic symptom patters occurring during the long-term course of psychiatric diseases, Leonhards classification requires that all the clinical features fit for a diagnosis to be made. Always using his own life-long case studies, Leonhard divided the endogenous psychoses into five main nosological groups: on the one hand, the prognostically favourable unipolar affective psychoses, bipolar affective psychoses and cycloid psychoses, and, on the other hand, the prognostically unfavourable unsystematic and systematic schizophrenia. In the meantime, the reliability and validity of this classification have been confirmed by scientific studies and early results provide guidelines for the different origins and varied therapeutic approaches for the specific disease profiles.

Clinical Pictures of Phasic Psychoses (without Cycloid Psychoses).- Manic-Depressive Illness.- Pure Melancholia and Pure Mania.- Pure Depressions and Pure Euphorias.- The Cycloid Psychosis.- Anxiety-Happiness Psychosis.- Excited-Inhibited Confusion Psychosis.- Hyperkinctic-Akinctic Motility Psychosis.- The Unsystematic Schizophrenias.- Affective Paraphrenia.- Cataphasia (Schizophasia).- Periodic Catatonia.- The Systematic Schizophrenias.- Simple Systematic Schizophrenias.- Combined Systematic Schizophrenias.- Comments.- Age of Onset, Sex Incidence, Course.- Statistical Findings from Investigations before 1968.- Statistical Findings from Investigations after 1968.- The Question of Endogenous Mixed Psychosis.- Etiology of Endogenous Psychoses.- Significance of Hereditary Disposition.- Significance of Psychosocial Circumstances.- Exogenous and Constitutional Causes of the Unsystematic Schizophrenias.- Exogenous and Constitutional Causes of Cycloid Psychoses.- Exogenous and Constitutional Causes of Manic.- Illness.- Exogenous and Constitutional Causes of Pure Phasic Psychoses.- Early Childhood Catatonia.- Delineation of Early Childhood Catatonia.- The Question of Organicity Underlying the Clinical Picture.- Diagnosis of Childhood Schizophrenia.- Distribution of Individual Forms of Early Childhood Catatonia ...- Distinguishing Early Childhood Catatonia from Mental Retardation.- Clinical Pictures of Early Childhood Catatonia.- Etiology of Early Childhood Schizophrenia.- Karl Leonhard's Life (1904-1988).- References.